Multi-component mixtures of bright red disperse azo dyestuffs

ABSTRACT

Coupling products of diazotized o- or p-toluidines to 3-hydroxy-2-naphthoic acid p-anisidide do not produce optimum dyeing properties in HT exhaustion dyeing of wound packages of synthetic fiber materials. Filtration occurs time after time under critical conditions, since these single dyestuffs and also mixtures of these with one another build up too slowly in the heating-up phase. 
     A bright red multi-component system of the same color shade, which exhibits a significantly improved exhaustion capacity by synergism during HT dyeing of wound packages and no longer presents difficulties in respect of filtration, can be obtained by mixing monoazo dyestuffs which are obtained by coupling diazotized aniline and p-toluidine in each case to 3-hydroxy-2-naphthoic acid p-anisidide.

DESCRIPTION

The present invention relates to dyestuff preparations in the form of amulti-component mixture of bright red disperse azo dyestuffs and theiruse for dyeing synthetic fibers.

Dyeing of synthetic fiber materials with disperse dyestuffs byexhaustion from an aqueous medium using. HT dyeing conditions attemperatures between 105° and 140° C. is general prior art and ispracticed on an industrial scale.

Disperse dyestuffs are by nature water-insoluble chemical compoundswhich contain no solubility-conferring grouping in the molecule. Asorganic color pigments, they are usually employed from an aqueousdispersion in colloidal form for dyeing hydrophobic synthetic fibers,such as, for example, 21/2 acetate, triacetate, polyamide or polyesterfiber types, and for this purpose they first have to be brought into anabsorbable, appropriately standardized fine dispersion by means of aso-called finish, advantageously under the co-influence of nonionic oranionic dispersing agents and, if appropriate, other auxiliaries.Without such a pre-treatment or such additives, it would not be possibleto achieve a stain-free and even dyeing of the substrate.

However, as the expert in the field of operation mentioned knows, thereare difficulties in the case of dyeing with bright red color shadesinasmuch as on the one hand the number of single dyestuffs having thedesired shading capacity is very limited, and in addition all theindividual dyestuffs suitable for this purpose have the disadvantagethat when used for high temperature dyeing of wound packages, that is tosay chiefly for cheeses and warp beams, under critical conditions--evenwith the best possible finish--they often tend towards filtration andtherefore to dyeings which are not fast to rubbing. The build-up of suchsingle dyestuffs in the heating-up phase, which is critical for theresult of the dyeings, is also usually too slow and thereforeunsatisfactory because for this reason dyeing temperatures which extendto the upper limit of the tolerance for the dyestuff and fiber and longdyeing times always become necessary.

The coloring agents in question on the basis of the inadequaciesdiscussed in respect of the dyeing results which can be achieved are,above all, the disperse dyestuffs of the type C.I. Disperse Red 200,C.I. Disperse Red 151 and the like.

In view of the state of affairs described above, the object was thus todevelop bright red disperse dyestuffs having faultless processcharacteristics in respect of dyeing properties, build-up and dispersionstability for the production of standard and combination dyeings onsynthetic fibers by the exhaustion technique under high temperature (HT)conditions, and of realizing this aim using high-performancecombinations based on two or three specifically selected red dispersedyestuffs. The aspect that filtration of non-fixed dyestuff on the goodsmust be avoided without fail was also essential, especially in view ofthe use of the coloring agents in question in the dyeing of woundpackages.

According to the invention, the solution to the object aimed at/by theexpert has now been found in that the disadvantages mentioned for redsingle dyestuffs of the abovementioned type in HT exhaustion dyeing of,in particular. PES fibers can be avoided by planned use of a combinationof the azo compounds described below.

The present invention accordingly relates to dyestuff preparations inthe form of a multi-component mixture of red disperse azo dyestuffs,which consist of

80 to 20 parts by weight, preferably 70 to 25 parts by weight, of thedyestuff of the formula I ##STR1## and 20 to 80 parts by weight,preferably 25 to 70 parts by weight, of the dyestuff of the formula II##STR2## and, as the shading component, 0 to 20 parts by weight,preferably 5 to 15 parts by weight, of the dyestuff C.I. Vat Red 41having the C.I. No. 73300 and corresponding to the formula III ##STR3##or contain these dyestuffs, with the proviso that the sum of theproportions of the single dyestuffs on which the mixture is based ineach case makes up a total weight of the preparation of 100 parts byweight and (in the case of commercial products) is based on the contentof pure dyestuff.

The dyestuff mixtures according to the invention contain or consist inprinciple of the two monoazo dyestuffs of the formulae I and II. Inaddition to these basic constituents, on which the abovementioned weightratios are based, they can moreover also include conventionalstandardizing agents and/or auxiliaries and, if appropriate, also otherdyestuffs, such as, for example, the vat dyestuff of the formula III.

However, the achievement of the inventive idea defined above was in noway obvious. In view of the doctrine of the relevant prior art, in fact,it was not to be assumed that providing a mixture of primarily azocompounds of the formulae I and II in the ranges of amounts claimed forproducing bright red HT exhaustion dyeings on synthetic fibers wouldlead to results which fulfil all the requirements in respect of build-upand even dyeing capacity and dispersion stability in the aqueous liquorto the optimum.

A finding qualified to this extent was not to be expected because of theknown exhaustion properties of the single dyestuffs under HT conditions,especially since chiefly the component of the formula I taken byitself--even with the best finish--reveals the deficiencies objected to.The red azo compound of the formula I, which is classified asproblematical as a result of such experiences, contains p-toluidine asthe diazo component. If this constituent of the formula I in thedyestuff preparation claimed is now combined with the isomeric dyestuffwhich contains o-toluidine as the diazo component and the same couplingcomponent (European Patent 0,185,207), a red isomer mixture whichlikewise has adverse properties during HT exhaustion dyeing of woundpackages. Under these circumstances, it was thus all the moreastonishing that the dyestuff mixture according to the inventioncontaining the component of the formula II which includes unsubstitutedaniline as the diazo component and differs from the two azo compoundspreviously discussed merely by the absence of the CH₃ group in theortho- or para-position, produces utilizable results because of asynergistic effect. As has been confirmed by experimental studies, ithas thus been found, surprisingly, that mixtures of several of thesesingle dyestuffs have synergistic characteristics in affinity behavioronly if quite particular structural features exist, whereas mixtures ofother dyestuffs do not achieve a better affinity behavior than thecorresponding single dyestuffs.

The component of the formula III optionally present in the dyestuffpreparations serves exclusively for certain shading possibilities sothat commercially available red single dyestuffs can be replaced,remaining largely faithful to the color shade, without changing therecipe.

For the manufacture of the preparations according to the invention, itis meanwhile unimportant whether the individual dyestuffs on which theyare based are combined as dyestuffs which are already in the finalfinished form (which otherwise prove to be largely inadequate when usedas a single component for the intended purpose), or whether they areexposed to the influence of a finishing process together as apre-finished mixture. However, the preparations claimed can also beobtained by diazotizing a combination of p-toluidine and aniline in aweight ratio of (80 to 20):(20 to 80), preferably (70 to 25):(25 to 70)and then coupling the diazotization product to the coupling component3-hydroxy-2-naphthoic acid p-anisidide, after which the multi-componentmixture of the individual dyestuffs of the formulae I and II produced inthis way by mixed coupling or any mixed crystals formed therefrom issubjected to a customary finish treatment, if appropriate withparticipation of the dyestuff of the formula III, and tostandardization. These circumstances just described give an indicationthat it is not any particular finish, but a synergism which isresponsible for the advantageous effect achieved.

Dyestuff preparations which have the features according to the inventionand are present in the form of a fine dispersion (in the state ready fordyeing) which results, for example, from grinding by means of dispersingagent(s), are outstandingly suitable for exhaustion dyeing of knownsynthetic fibers by themselves or as a constituent of mixturescontaining such synthetic fibers and natural fibers or regeneratedfibers under high-temperature conditions (105°-140° C.) of the aqueousdyeing medium. According to the present invention, they are employed asa disperse red dyestuff for achieving, above all, bright redstandardized color shades on the synthetic fibers or on the syntheticfiber component of fiber mixtures, or also combination color shades. Thepresent invention at the same time furthermore relates to a dyeingprocess of the type mentioned and the use of the novel dyestuffpreparations on the basis mentioned.

Synthetic fiber goods which can be colored by means of the dyestuffpreparations described according to the invention by their structure areprimarily hydrophobic polyester fibers based on polyethyleneterephthalate, polybutylene terephthalate or polycyclohexyleneterephthalate, and also fibers which are derived from copolymers of suchPES.

The present invention can be used in principle for dyeing theabovementioned fiber materials in various states of processing, forexample as flocks, slubbings, yarn or piece goods.

Dyeing of synthetic fibers or mixtures thereof using the dyestuffmixtures according to the invention is carried out by the conventionalhigh-temperature (HT) exhaustion method at temperatures between 105° and140° C. The actual dyeing is advantageously followed by reductivepurification or after-treatment, assisted by dispersing agents, of thedyed goods for the removal of dyestuff portions which are not completelyfixed.

The following embodiment example is intended to demonstrate the effectwhich can be achieved by the invention without limiting it, above all inrespect of the mixing ratios stated.

EXAMPLE

A cheese of polyester filament weighing 300 g is dyed on a dyeingapparatus equipped for the treatment of wound packages using an aqueousdispersion which contains--based on the weight of the dry goods--2.5% ofa mixture of already-finished dyestuffs in the commercially availableform composed of

60 parts by weight of the dyestuff of the formula I 28 parts by weightof the dyestuff of the formula II and

12 parts by weight of the dyestuff of the formula III

the pH of which has first been adjusted to 5, in a liquor ratio of 1:15under an alternating liquor circulation direction at 135° C. for 90minutes.

Reductive after-purification customary in practice is carried out forfinishing the yarn dyeing.

A bright red dyeing of the goods which is fast to rubbing is obtained,without filtration of non-fixed dyestuffs.

COMPARISON

The above exhaustion dyeing was repeated under the same conditions, withthe exception that instead of the dyestuff mixture, 2.5%--based on theweight of goods--of the dyestuff of the formula I in the finished,commercially available form was employed.

A dyeing of the yarn which has the same color shade but is not fast torubbing and in many cases is unusable because of filtration of thedyestuff is obtained.

If the affinity properties of the particular coloring agent during thedyeing operation are now checked in the case of the dyeing testpreviously performed, a more uniform, coloristic build-up which startsearlier manifests itself in the example--compared with the comparison.Filter samples of aqueous liquors of the two dyestuff preparations showthat the single dyestuff (Comparison) tends to produce undesirabledeposits between layers of the wound material, whereas the dyestuffmixture (Example) proved to be perfectly good in this respect.

We claim:
 1. A dyestuff preparation in the form of a multi-componentmixture comprising red disperse azo dyestuffs, which comprises80 to 20parts by weight, of the dyestuff of the formula I ##STR4## and 20to 80parts by weight, of the dyestuff of the formula II ##STR5## and, as theshading component, 0to 20 parts by weight, of the dyestuff C.I. Vat Red41 having the C.I. No. 73300 and corresponding to the formula III##STR6## with the proviso that the sum of the proportions of theindividual dyestuffs on which the mixture is based in each case makes upa total weight of the preparation of 100 parts by weight and is based onthe content of pure dyestuff.
 2. The dyestuff preparation as claimed inclaim 1, in which the mixing ratio of the individual dyestuffs on whichthe mixture is based is70 to 25 parts by weight of the dyestuff of theformula I, 25 to 70 parts by weight of the dyestuff of the formula IIand 5 to 15 parts by weight of the dyestuff of the formula III, and atthe same time the proviso formulated in that claim is complied with. 3.The dyestuff preparation according to claim 1, in which the mixturecomprising the disperse dyestuffs of the formulae I and II andoptionally of the vat dyestuff of the formula III is present in the formof a fine dispersion, in the state ready for disperse dyeing.
 4. Thedyestuff preparation as claimed in claim 3, obtainableby mixing theindividual basic dyestuffs of the formulae I and II and optionally ofthe formula III, which have been separately completely finished andstandardized beforehand, or by mixing the non-finished individual basicdyestuffs of the formulae I and II and optionally of the formula III andcarrying out joint finishing and standardization subsequently or evenduring the mixing operation, or by finishing a multi-component mixture,obtained by joint azo coupling of the diazonium compounds of acombination of p-toluidine and aniline in a weight ratio of (80 to20):(20 to 80) to 3-hydroxy-2-naphthoic acid p-anisidide, of theindividual dyestuffs of the formulae I and II, or of any mixed crystalformed therefrom, and standardizing, optionally with participation ofthe dyestuff of the formula III.
 5. A process for exhaustion dyeing oftextile material comprising synthetic fibers alone or in combinationwith natural fibers or regenerated fibers or combinations of natural andregenerated fibers under high temperature (HT) conditions, whichcomprises dyeing said textile material with a dyestuff preparation asclaimed in claim 1 as the disperse red dyestuff for standard andcombination dyeings.
 6. The process as claimed in claim 5, wherein woundpackages are dyed by exhaustion at temperatures between 105° and 140° C.7. A textile material comprising synthetic fibers, which has been dyedwith a dyestuff preparation as claimed in claim
 1. 8. A textile materialcomprising synthetic fibers, which has been dyed by a process as claimedin claim
 5. 9. A textile material comprising synthetic fibers which hasbeen dyed by a process as claimed in claim
 6. 10. A dyestuff preparationas claimed in claim 4, wherein said combination of p-toluidine andaniline is in a weight ratio of (70 to 25):(25 to 70).